EEACTIOiSS IN BLAST FURNACES 737 



with those of irou smeltiug; but the followiug experimeuts, innde by I. L. Bell iu the 

 iron blast furuaces iu the preseuce of the gases actually produced iu smeltiug, show 

 with more accuracy the real process of the reduction of irou: 



(«) Furuace working with raw limestone; pieces of calcined Cleveland ore or 

 artificial hematite kept for two hours iu the zone of the furnace below red ))oiut. 

 Composition of gases: CO=100 volumes; C02=25 volumes; ]Sr=190 volumes. The 

 ore loses 11.85 per cent, of its oxygen (meau of two experiments). 



(b) Same experiment as iu a, but in cherry-red zoue. Composition of gases: 

 C !=100 volumes; COi=Si volumes; N=172i volumes. The ore loses 76.2 per cent, 

 of its oxygen, showing great reduction of iron. 



(c) Same experiment as in a and b, but in bright-red zone. Comijosition of gase.-^ : 

 CO=100 volumes; COj^S^ volumes; N=;169i volumes. The ore loses 73.8 per cent, 

 of its oxygen. 



(d) Same experiment as preceding, but iu very bright-red zone. Composition of 

 gases: CO = 100 volumes; C02=3 volumes; X= 18.3 J volumes. The ore loses 80 per 

 cent, of its oxygen. 



(e) Same experimeut as preceding, but in intensely bright-red zone near tuyeres. 

 Composition of gases: CO^lOO volumes; C02=.5 volumes; N=172^ volumes. The 

 ore loses 71 per cent, of its oxygen. 



To interpret correctly these experiments we must take into consideration that 

 the ore does not remain exposed two hours to the influence of the gases of the same 

 zone in the furuaces of Leadville, and that although the reducing jiower of the cor- 

 responding zones is sensibly the same the quantity of ore reduced is greatly dimin- 

 ished. 



Reactionsof sulphides of iron — Pyrites existing in some ores and sulphide of iron 

 being formed iu the furuace, the following reactions are interesting: 



No. 50. — Protosulphide of iron and peroxide of irou act upon each other with 

 formation of magnetic oxide of iron and sulphurous acid: FeS4-10Fe:.O3=7Fe3 O4 

 + SO2 (Percy-Hochstatter). To this reaction is probably due iu part the magnetic 

 oxide of mattes. 



No. 5'. — Iron pyrites and oxide of lead react upon each other, give off sulphurous 

 acid, and form a magnetic mixture of sulphides and oxides of lead and iiou (Percy). 

 In this instance the origin of mattes is clearly indicated. 



CHEMICAL DISCUr;SION OF THE LEADVILLE Ft'ENACES. 



The object of this discussion is to illustrate the chemical and metallurgical i-e- 

 actions of the blast furuace, and it is based as much as possible on general averages 

 obtained during the preparation of this report. 



It has already been seen (Table IV) : 



(1) That the average propoi-tion of fuel to ore is 32.83 per cent. 



(2) That the average proportion of fuel to charge is 24.03 per cent. 



(3) That the average composition of the fuel used iu the camp is: charcoal, 57 

 per cent.; coke 43 per cent. = 100 per cent. 



(4) That the average proportion of ash in coke is 22 per cent, and in charcoal 

 2.0 per cent., giving for the fuel under consideration au average of 10.88 per (Ttnt. of 



M0^" XII 47 



